Seems like there is potential to add a lot to this.

[BebeSparkelSparkel]

Hey I've been interested in getting better collection objects but it would be nice to have more people involved in this. There is a repo called more-collections and it could be nice to involve them because they seem very responsive.

[maweki]

You seem to have linked to a repo that is called more-itertools, which is very nice. This here repo came into existence because I didn't like the multiset-implementation in https://github.com/mlenzen/collections-extended.

I am open to collaborations.